Fung said scientists can do filtration on the samples to filter but with that process you still have the inhibitors in the liquid, which may in turn lead to false reads because the inhibitors will alter the PCR reaction.

"The less inhibitor the better," Fung said.

Where the stomacher pulverizes the sample, Fung said the pulsifier literally shakes pathogens into the liquid without breaking up the food extensively. In turn, the pulsified samples are much cleaner in terms of the turbidity and much easier to operate.

"This is the first step of testing in food microbiology -- to blend your food first," Fung said. "This method will give you the same number of pathogens but the liquid is much clearer.

Fung said while many people study pathogens in relation to meat and poultry contamination, but the study of contamination in vegetables is often neglected.

"We make zillions of salads and send to the grocery stores, but there is no control," Fung said. "The only control of little packages of salad is low temperatures but some pathogens can survive and grow in low temperatures."

As opposed to foods that are cooked, Fung said prepared salad mixes are just opened -- sometimes washed -- and dumped into a bowl and eaten.

"This is an interesting experiment," Fung said "From a scientific standpoint, we're going to find out how and why the organisms are shaken into the liquid. We will be an electron microscope and looking at lettuce leaves to find out the difference between the pulsified and the stomacher samples and see if they are giving the same numbers (of pathogens). Because of our previous data I think it will show that they are."

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Contact: Daniel Y.C. Fung
danfung@k-state.edu
785-532-1208
Kansas State University
14-Nov-2002